Mallard de La Varende et al. showed that gut dysbiosis following treatment with antibiotics or antibiotic-associated species led to loss of secondary bile acids (BAs), increased tauro-conjugated primary BAs, downregulation of MAdCAM-1 in the ilium, and increased γ-glutamyl transferase (γ-GT) in serum, supporting TIME reprogramming, T cell exhaustion, and resistance to anti-PD-1 in tumor-bearing mice. Resistance could be overcome by performing FMT, supplementing secondary BAs, or using an ilium-specific FXR agonist. In patients, resistance was associated with subclinical cholestasis (elevated γ-GT), which predicted poor response.

Contributed by Lauren Hitchings

ABSTRACT: Gut dysbiosis compromises cancer immunosurveillance by downregulating ileal mucosal addressin cell adhesion molecule 1 (MAdCAM-1), but the metabolic landscape associated with gut dysbiosis remains elusive. Here, we show that antibiotics (ABX) or ABX-associated Enterocloster species lead to the loss of secondary bile acids (BAs) including deoxycholic acid (DCA) and the accumulation of tauro-conjugated primary BAs (tauro-chenodeoxycholic acid [TCDCA] and tauro-β-muricholic acid [T-βMCA]) from the alternative pathway in the plasma of patients and mice. Fecal microbial transplantation (FMT), the ileum-specific farnesoid X receptor (FXR) agonist fexaramine, or glycodeoxycholic acid (GDCA) compen- sated dysbiosis-associated BA abnormalities and circumvent primary resistance to PD-1 blockade. GDCA curtailed ABX-induced MAdCAM-1 downregulation and T cell exhaustion in tumors. Subclinical cholestasis defined by elevation of γ-glutamyl transferase (γGT) correlated with increased TCDCA and decreased sMAdCAM-1 in plasma and predicted poor survival in multivariate analyses in six cohorts of patients who received immunotherapy. Hence, subclinical cholestasis accompanies gut dysbiosis, paving the way to immunoresistance.

Author Info: 1- Université Paris-Saclay, Gustave Roussy (GRCC), ClinicObiome, Inserm UMR1367, Microbiota and Mucosal Immunity for Cancer Immunotherapy, 94805 Villejuif, France. 2- Centre de rec herche Du CHUM (CRCHUM), Montréal, QC H2W1T8, Canada. 3- Centre de Recherche des Cordeliers, INSERM U1138, Equipe Labellisée – Ligue Nationale Contre le Cancer, Université Paris Cité, Sorbonne Université, 75006 Paris, France. 4- Unidad de Excelencia, Instituto de Biomedicina y Genética Molecular de Valladolid, Consejo Superior de Investigaciones Científicas-Universidad de Valladolid, 47001 Valladolid, Spain. 5- MetaGenoPolis, INRAe, Université Paris-Saclay 78350 Jouy en Josas, France. 6- Université Paris-Saclay, INSERM US23, Analyse moléculaire, modélisation et imagerie de la maladie Cancéreuse, Plateformes de Métabolomique et de Criblage Cellulaire Haut Débit, 94805 Villejuif, France. 7- Université Paris-Saclay, Gustave Roussy, U1356 Next Generation Immuno-Oncology Research, 94805 Villejuif, France